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            <small>
              <a href="#Procedure">Procedure<br></a>
              <a href="#Abstract">Abstract<br></a>
              <a href="#Required_Reading">Required_Reading<br></a>
              <a href="#Keywords">Keywords<br></a>
              <a href="#Brief_I/O">Brief_I/O<br></a>
              <a href="#Detailed_Input">Detailed_Input<br></a>

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              <small>               <a href="#Detailed_Output">Detailed_Output<br></a>
              <a href="#Parameters">Parameters<br></a>
              <a href="#Exceptions">Exceptions<br></a>
              <a href="#Files">Files<br></a>
              <a href="#Particulars">Particulars<br></a>
              <a href="#Examples">Examples<br></a>

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              <small>               <a href="#Restrictions">Restrictions<br></a>
              <a href="#Literature_References">Literature_References<br></a>
              <a href="#Author_and_Institution">Author_and_Institution<br></a>
              <a href="#Version">Version<br></a>
              <a href="#Index_Entries">Index_Entries<br></a>
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<h4><a name="Procedure">Procedure</a></h4>
<PRE>
   void vprjp_c ( ConstSpiceDouble    vin   [3],
                  ConstSpicePlane   * plane,
                  SpiceDouble         vout  [3] ) 

</PRE>
<h4><a name="Abstract">Abstract</a></h4>
<PRE>
 
   Project a vector onto a specified plane, orthogonally. 
 </PRE>
<h4><a name="Required_Reading">Required_Reading</a></h4>
<PRE>
 
   <a href="../req/planes.html">PLANES</a> 
 </PRE>
<h4><a name="Keywords">Keywords</a></h4>
<PRE>
 
   GEOMETRY 
   MATH 
   PLANE 
   VECTOR 
 

</PRE>
<h4><a name="Brief_I/O">Brief_I/O</a></h4>
<PRE>
 
   Variable  I/O  Description 
   --------  ---  -------------------------------------------------- 
   vin        I   Vector to be projected. 
   plane      I   A CSPICE plane onto which vin is projected. 
   vout       O   Vector resulting from projection. 
 </PRE>
<h4><a name="Detailed_Input">Detailed_Input</a></h4>
<PRE>
 
   vin            is a 3-vector that is to be orthogonally projected 
                  onto a specified plane. 
 
   plane          is a CSPICE plane that represents the geometric 
                  plane onto which vin is to be projected. 
 </PRE>
<h4><a name="Detailed_Output">Detailed_Output</a></h4>
<PRE>
 
   vout           is the vector resulting from the orthogonal 
                  projection of vin onto plane.  vout is the closest 
                  point in the specified plane to vin. 
 </PRE>
<h4><a name="Parameters">Parameters</a></h4>
<PRE>
 
   None. 
 </PRE>
<h4><a name="Exceptions">Exceptions</a></h4>
<PRE>
 
   1)  Invalid input planes are diagnosed by the routine <a href="pl2nvc_c.html">pl2nvc_c</a>, 
       which is called by this routine. 
 </PRE>
<h4><a name="Files">Files</a></h4>
<PRE>
 
   None. 
 </PRE>
<h4><a name="Particulars">Particulars</a></h4>
<PRE>
 
   Projecting a vector v orthogonally onto a plane can be thought of 
   as finding the closest vector in the plane to v.  This `closest 
   vector' always exists; it may be coincident with the original 
   vector. 
 
   Two related routines are <a href="vprjpi_c.html">vprjpi_c</a>, which inverts an orthogonal 
   projection of a vector onto a plane, and <a href="vproj_c.html">vproj_c</a>, which projects 
   a vector orthogonally onto another vector. 
 </PRE>
<h4><a name="Examples">Examples</a></h4>
<PRE>
 
   1)   Find the closest point in the ring plane of a planet to a 
        spacecraft located at positn (in body-fixed coordinates). 
        Suppose the vector normal is normal to the ring plane, and 
        that origin, which represents the body center, is in the 
        ring plane.  Then we can make a `plane' with the code 
 
           pnv2pl_c ( origin, normal, &amp;plane ); 
 
        can find the projection by making the call 
 
           <b>vprjp_c</b> ( positn, &amp;plane, proj ); 
 </PRE>
<h4><a name="Restrictions">Restrictions</a></h4>
<PRE>
 
   None. 
 </PRE>
<h4><a name="Literature_References">Literature_References</a></h4>
<PRE>
 
   [1] `Calculus and Analytic Geometry', Thomas and Finney. 
 </PRE>
<h4><a name="Author_and_Institution">Author_and_Institution</a></h4>
<PRE>
 
   N.J. Bachman   (JPL) 
 </PRE>
<h4><a name="Version">Version</a></h4>
<PRE>
 
   -CSPICE Version 1.0.0, 05-MAR-1999 (NJB)
</PRE>
<h4><a name="Index_Entries">Index_Entries</a></h4>
<PRE>
 
   vector projection onto plane 
 </PRE>
<h4>Link to routine vprjp_c source file <a href='../../../src/cspice/vprjp_c.c'>vprjp_c.c</a> </h4>

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   <pre>Wed Jun  9 13:05:32 2010</pre>

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